In A Midsummer Night's Dream, why is Act II called the "rising action"? What is an example of character conflicts in Act I?

The rising action in a dramatic narrative is the combination of events that occur after the exposition and ultimately lead to the play's climax. The rising action intensifies the plot and lends dramatic or comic interest. Shakespeare's dramatic works and comedies are characterized by very complex plots, so the rising action is usually a series of events involving any number of characters. This is evident in the intricate comedy of A Midsummer Night's Dream.
There are at least two rising actions. The first occurs when two sets of lovers, caught up in a complex love triangle, are meddled with by a fairy in the woods. Demetrius and Helena were once betrothed, but he breaks it off when he falls in love with Hermia. Lysander and Hermia plan to elope and run to the woods; Demetrius and Helena follow them. At first there are two men in love with Hermia and none in love with Helena; when the fairy Puck (Robin Goodfellow) intervenes, he gets it wrong and makes both men fall in love with Helena. This causes Helena and Hermia to fight as well.
The second rising action, one that is connected to the second part of your question, is the argument between Oberon and Titania, the king and queen of the fairies. We learn in Act I that they are in conflict because Titania has been raising a baby boy and Oberon wants to take charge of him. The disagreement between the four lovers inspires Puck to put a spell on them, but Titania, who runs off to avoid Oberon, is caught up in the spell and falls in love with Bottom, an actor taking part in a play for the wedding of Theseus and Hippolyta (who are the de facto "monarchs" of the realm of the court where the lovers live; they parallel Oberon and Titania, and in some productions, these two pairs of characters are played by the same actors). When Oberon learns of Titania's humiliation, he takes great pleasure in it.